I like my 40's better and get out to two miles quite often. But I'm using the 320, it seems to pick them up a lot better than my 220 did.
It also depends on where you are hunting. Some areas have piss poor gps reception for some reason.
Your right, some areas have better reception than other.
I've wondered alot if it has to do with iron ore close to the surface? an acquaintance of my boss's in Utah says he can get 2 miles easy in the mountain country and has even seen 4 miles on his screen. I for the record highly doubt that.
Other factors may be phone towers don't you think? I've seen that good reception on my iPhone means good reception on te garmin, BUT, too close to a tower and I get odd
Results, or too close to high voltage overhead line right of ways does the say thing.